Half the World's Vitamin D Deficiency Treatable, but what is Safe?

A leading expert in Vitamin D says levels of the sunshine vitamin are too low in over half of the world's population but could be treated with a combination of diet, sun and vitamin D supplements. Half the people in North America and Western Europe get insufficient amounts of vitamin D according to Anthony Norman, a University of California Riverside international expert on vitamin D and distinguished professor emeritus of biochemistry and biomedical sciences who says more studies are needed to find out if too much vitamin D could cause harm.

Too little vitamin D can lead to an array of health problems but experts also say too much could do the same. To date there has been no consensus as to optimal dosing or how to get enough of the vitamin to keep immunity intact, decrease the chances of cancer, maintain bone health, decrease asthma risk, prevent rheumatoid arthritis, diabetes, ensure a healthy heart, avoid obesity and keep muscles strong - all of which are health risks linked to low vitamin D levels.

According to Dr. Norman, "...given that two-thirds of the people are vitamin D-insufficient or deficient, it is clear that merely eating vitamin D-rich foods is not adequate to solve the problem for most adults.” For the more than half of the world's population that have inadequate vitamin D levels, he recommends a combination of supplements, foods fortified with vitamin D and maybe just enough sunshine to produce a tan.

"There is a wide consensus among scientists that the relative daily intake of vitamin D should be increased to 2,000 to 4,000 IU for most adults," Norman says. "A 2000 IU daily intake can be achieved by a combination of sunshine, food, supplements, and possibly even limited tanning exposure."

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Dr. Norman points out the importance of more research fo find out if boosting vitamin D levels that affect over half of the world is good or bad. Foods that are fortified provide about 400 IU per serving.

"The benefits of more research on the topic justifies why this field of research deserves additional governmental funding," he says. "Already, several studies have reported substantial reductions in incidence of breast cancer, colon cancer and type 1 diabetes in association with adequate intake of vitamin D, the positive effect generally occurring within five years of initiation of adequate vitamin D intake." But despite preliminary evidence, long-term vitamin D studies are lacking.

“There is a conundrum. How can a physician of a government recommend major increases in vitamin D intake, without appropriate evidence-based research studies on very large groups, for example, 2,000 IU for 3 to 5 years, to ensure safety?” Norman said.

Dr. Norman who has been researching vitamin D for over 50 years says the evidence is "irrevocable" that the immune system, pancreas, heart-cardiovascular, muscle and brain systems "generate biological responses' to vitamin D. Receptors are present throughout the body, but until studies are funded recommending optimal amounts of vitamin D cannot be recommended.

Researchers still warn that more studies are needed to ensure there are no adverse effects from too much vitamin D. Vitamin D can be obtained by eating natural and vitamin D fortified foods, from supplements and sunshine - but how much vitamin D is safe remains a question.